Breathing gas delivery method and apparatus

Abstract

An improved methodology and apparatus for delivery of breathing gas such as fop the treatment of sleep apnea through application of alternating high and low level positive airway pressure within the airway of the patient with the high and low airway pressure being coordinated with the spontaneous respiration of the patient.

We claim: 
     
       1. A method of providing a flow of gas within a predetermined flow path which includes a patient's respiratory system for breathing by such a patient in repeated breathing cycles each including an inspiratory phase during which said flow of gas includes gas flowing to such a patient's lungs and an expiratory phase during which said flow of gas includes gas flowing from such a patient's lungs, said method comprising the steps of: providing said flow of gas at a positive pressure at least equal to ambient atmospheric pressure to maintain the patient's airway at such a positive pressure during said repeated breathing cycles;   monitoring said flow of gas;   from said monitoring, determining at least one of an instantaneous flow rate and an average flow rate of such gas;   utilizing said at least one of said instantaneous flow rate and said average flow rate to identify the occurrence of said inspiratory and expiratory phases; and   coordinating the patient's airway pressure with said occurrence of each said inspiratory and expiratory phases in a manner that said positive pressure is maintained in the patient's airway during a sequence of said inspiratory and expiratory phases with the magnitude of said positive pressure during selected ones of said expiratory phases in said sequence being less than the magnitude of said positive pressure during the respective immediately preceding inspiratory phases.   
     
     
       2. The method as set forth in claim 1 wherein said determining step includes determining at least one of said instantaneous and average flow rates of such gas flowing between such a source and the airway of such a patient. 
     
     
       3. The method as set forth in claim 1 wherein said supplying step includes the supplying of breathing gas under pressure via a breathing appliance interfacing with such a patient. 
     
     
       4. The method as set forth in claim 1 wherein said positive pressure is maintained in the patient's airway substantially continuously during said sequence of said inspiratory and expiratory phases. 
     
     
       5. The method as set forth in claim 1 wherein said monitoring of said flow of gas is continual monitoring thereof. 
     
     
       6. The method as set forth in claim 1 wherein said determining at least one of an instantaneous flow rate and an average flow rate is continual determining thereof, 
     
     
       7. The method as set forth in claim 1 wherein said determining step includes determining both of said instantaneous flow rate and said average flow rate, and said utilizing step includes utilizing both of said instantaneous flow rate and said average flow rate. 
     
     
       8. The method as set forth in claim 1 wherein at least one of said magnitudes of said positive pressure is a substantially constant magnitude of positive pressure. 
     
     
       9. A method of medical treatment for a patient comprising the steps of: providing a flow of breathing gas from a source for delivery to the airway of such a patient at selected higher and lower pressure magnitudes at least as great as ambient atmospheric pressure and permitting said flow of gas to pass from the patient;   monitoring said flow to detect an instantaneous flow rate of such breathing gas;   processing selected parameters including said instantaneous flow rate to provide a reference indicia corresponding to an average flow rate of such breathing gas; and   utilizing at least one of said instantaneous flow rate and said reference indicia to select one of said higher and said lower pressure magnitudes to be applied in the airway of such a patient.   
     
     
       10. The method as set forth in claim 9 wherein said monitoring step includes monitoring said flow of gas to detect an instantaneous flow rate of such breathing gas flowing between said source and the airway of such a patient. 
     
     
       11. The method as set forth in claim 9 including the additional step of continually repeating said selecting step. 
     
     
       12. The method as set forth in claim 9 wherein said flow of breathing gas is a substantially continuous flow of breathing gas. 
     
     
       13. The method as set forth in claim 9 wherein said selecting step includes selecting said higher pressure magnitude when said instantaneous flow rate is greater than said reference indicia, and selecting said lower pressure magnitude when said instantaneous flow rate is less than said reference indicia. 
     
     
       14. The method as set forth in claim 9 wherein said processing step includes adjusting a previously determined value of said reference indicia to provide an adjusted value thereof. 
     
     
       15. The method as set forth in claim 14 wherein said previously determined value of said reference indicia is included among said selected parameters. 
     
     
       16. The method as set forth in claim 15 wherein said processing step includes first processing of said instantaneous flow rate to provide a time average of the flow rate of breathing gas resulting from said providing step as a first component of said reference indicia. 
     
     
       17. The method as set forth in claim 16 wherein said processing step additionally includes second processing of said instantaneous flow rate and said reference indicia to provide a measure of the net flow of breathing gas to such a patient for each spontaneous patient breath as a second component of said reference indicia. 
     
     
       18. The method as set forth in claim 17 wherein said processing step additionally includes third processing of said instantaneous flow rate and the occurrence of said selecting step to provide a measure of said instantaneous flow rate at the end of selected patient expiratory cycles as a third component of said reference indicia. 
     
     
       19. The method as set forth in claim 18 wherein said first, second and third processing steps are carried out simultaneously. 
     
     
       20. The method as set forth in claim 19 wherein said simultaneous first, second and third processing steps are carried out repetitively. 
     
     
       21. The method as set forth in claim 20 wherein said third processing step overrides said second processing step when said measure of said instantaneous flow rate at the end of said selected patient expiratory cycles differs from said reference indicia. 
     
     
       22. The method as set forth in claim 9 wherein said providing step includes providing said flow of breathing gas via a breathing gas delivery appliance worn by such a patient. 
     
     
       23. The method as set forth in claim 9 wherein said monitoring of said flow of gas includes continual monitoring thereof. 
     
     
       24. The method as set forth in claim 9 wherein said processing selected parameters includes continual processing thereof. 
     
     
       25. The method as set forth in claim 9 wherein said utilizing at least one of said instantaneous flow rate and said reference indicia includes utilizing both of said instantaneous flow rate and said reference indicia. 
     
     
       26. The method as set forth in claim 9 wherein at least one of said higher and lower pressure magnitudes is a substantially constant pressure magnitude. 
     
     
       27. An apparatus for delivering pressurized gas to the airway of a patient who is breathing in repeated breathing cycles each including an inspiratory phase and an expiratory phase comprising: a gas flow generator means for providing a flow of gas;   supply means for delivery of said flow of gas from said flow generator means to the airway of such a patient;   exhaust means for allowing said flow of gas to pass from the airway of such a patient;   pressure controller means cooperable with said flow generator means to provide said flow of gas within said supply means for delivery to the airway of such a patient at selectively variable pressures;   monitoring means for monitoring the flow-rate of said flow of gas;   processor means which is cooperable with said monitoring means to provide a first indicia corresponding to an instantaneous flow rate of said flow of gas;   said processor means being further cooperable with said monitoring means to provide a reference indicia corresponding to an approximate average flow rate of said flow of gas;   decision means operable to utilize at least one of said first indicia and said reference indicia to identify the occurrence of said inspiratory and expiratory phases; and   said decision means being cooperable with said pressure controller means to control the pressure of such gas within said supply means for varying the pressure applied within the airway of such a patient in response to identification of the occurrence of said inspiratory and expiratory phases.   
     
     
       28. The apparatus as set forth in claim 27 wherein said first indicia corresponds to an instantaneous flow rate of such gas in said supply means and said reference indicia corresponds to an approximate average flow rate of such gas in said supply means. 
     
     
       29. The apparatus as set forth in claim 27 wherein said decision means is operable to utilize both of said first indicia and said reference indicia, and is further operable to adjust said pressure controller means to provide a higher pressure within the airway of such a patient when said first indicia exceeds said reference indicia, and to provide a lower pressure within the airway of such a patient when said first indicia is less than said reference indicia. 
     
     
       30. The apparatus as set forth in claim 29 wherein said processor means includes processing elements operable to adjust an existing value of said reference indicia to provide an adjusted value thereof. 
     
     
       31. The apparatus as set forth in claim 30 wherein said processing elements include means for processing said first indicia to provide a time average of the flow rate of such gas within said supply means as a first component of said reference indicia. 
     
     
       32. The apparatus as set forth in claim 31 wherein said processing elements further include means for processing said first indicia and said reference indicia to provide a measure of the gas flow within said supply means during a predeterminable time period as a second component of said reference indicia. 
     
     
       33. The apparatus as set forth in claim 32 wherein said predeterminable time period is a single complete breathing cycle of such a patient including one inspiratory cycle and one expiratory cycle in sequence. 
     
     
       34. The apparatus as set forth in claim 33 wherein said processing elements further include means for processing said first indicia to provide a measure of the value of said first indicia at the end of any such complete breathing cycle by such a patient as a third component of said reference indicia. 
     
     
       35. The apparatus as set forth in claim 27 wherein said monitoring means is operable for continually monitoring the flow rate of said flow of gas. 
     
     
       36. The apparatus as set forth in claim 27 wherein said processor means includes first and second processor means, respectively, with one of said first and second processor means being cooperable with said monitoring means to provide said first indicia and the other of said first and second processor means being cooperable with said one of said processor means to provide said reference indicia. 
     
     
       37. The apparatus as set forth in claim 27 wherein said decision means is operable to utilize both of said first indicia and said reference indicia to identify the occurrence of said inspiratory and expiratory phases. 
     
     
       38. A method of treating sleep apnea syndrome comprising the steps of: providing a flow of breathing gas from a source for breathing by a patient;   supplying said flow of breathing gas to the airway of such a patient during inspiration;   permitting said flow of breathing gas to pass from such a patient during expiration;   monitoring said flow of breathing gas to detect flow conditions of said flow of breathing gas;   from said monitoring, determining at least one of an instantaneous flow rate and an average flow rate of said flow of breathing gas;   utilizing said at least one of said instantaneous flow rate and said average flow rate to identify the occurrence of each inspiratory and expiratory phase of the patient's respiration cycle; and   coordinating the patient's airway pressure with said occurrence of each said inspiratory and expiratory phase to maintain positive pressure in the patient's airway during a sequence of said inspiratory and said expiratory phases with the magnitude of said positive pressure maintained during selected ones of said expiratory phases in said sequence being less than the magnitude of said positive pressure maintained during the respective immediately preceding inspiratory phases.   
     
     
       39. The method as set forth in claim 38 wherein said determining step includes determining said at least one of an instantaneous flow rate and an average flow rate of said flow of breathing gas. 
     
     
       40. The method as set forth in claim 38 wherein said determining step includes continually determining at least one of an instantaneous flow rate and an average flow rate of such breathing gas. 
     
     
       41. The method as set forth in claim 38 wherein said determining at least one of an instantaneous flow rate and an average flow rate includes determining both of said instantaneous flow rate and said average flow rate, and said utilizing at least one of said instantaneous flow rate and said average flow rate includes utilizing both of said instantaneous flow rate and said average flow rate. 
     
     
       42. The method as set forth in claim 38 wherein the magnitude of said positive pressure maintained during at least one of said expiratory and said inspiratory phases is a constant magnitude of positive pressure. 
     
     
       43. The method as set forth in claim 38 wherein said positive pressure is maintained substantially continuously in the patient's airway. 
     
     
       44. A method of treating sleep apnea syndrome comprising the steps of: providing a flow of breathing gas from a source for delivery to the airway of a patient at selected higher and lower pressure magnitudes at least as great as ambient atmospheric pressure;   permitting said flow of breathing gas to pass from such a patient;   monitoring said flow of breathing gas to detect an instantaneous flow rate of said breathing gas;   processing selected parameters including said instantaneous flow rate to provide a reference indicia corresponding to an average flow rate of said breathing gas; and   utilizing at least one of said instantaneous flow rate and said reference indicia to select one of said higher and said lower pressure magnitudes for said supply flow of breathing gas.   
     
     
       45. The method as set forth in claim 44 wherein said instantaneous flow rate and average flow rate of said breathing gas are, respectively, instantaneous and average flow rates of said flow of breathing gas. 
     
     
       46. The method as set forth in claim 44 wherein said monitoring of said flow of breathing gas includes continual monitoring thereof. 
     
     
       47. The method as set forth in claim 44 wherein said processing selected parameters includes continual processing thereof. 
     
     
       48. The method as set forth in claim 44 wherein said utilizing at least one of said instantaneous flow rate and said reference indicia includes utilizing both of said instantaneous flow rate and said reference indicia. 
     
     
       49. A method of treating obstructive sleep apnea comprising the steps of: preventing episodes of airway obstruction by applying positive pressure greater than ambient atmospheric pressure within the airway of a patient;   applying said positive pressure by supplying gas at a positive pressure to the airway of such a patient;   adjusting the pressure of said gas in the patient's airway to coordinate the patient's airway pressure with the occurrence of alternating inspiratory and expiratory phases of the patient's respiration in a manner to maintain said positive pressure in the patient's airway during a sequence of said inspiratory and expiratory phases with the magnitude of said positive pressure during each said expiratory phase being less than the magnitude of said positive pressure during the immediately preceding inspiratory phase, respectively; and   maintaining the magnitude of said positive pressure within the patient's airway at a value sufficient to prevent said episodes of airway obstruction during said sequence of inspiratory and expiratory phases.   
     
     
       50. The method as set forth in claim 49 wherein said applying said positive pressure step includes substantially continuously applying said positive pressure. 
     
     
       51. The method as set forth in claim 49 wherein said adjusting the pressure of said gas in the patient's airway to coordinate the patient's airway pressure with the occurrence of alternating inspiratory and expiratory phases of the patient's respiration in a manner to maintain said positive pressure includes substantially continuously maintaining said positive pressure. 
     
     
       52. The method as set forth in claim 49 wherein the magnitude of positive pressure applied during at least said inspiratory phases or said expiratory phases is a substantially constant magnitude of positive pressure. 
     
     
       53. A method of treating sleep apnea syndrome comprising the steps of: providing a flow of breathing gas from a source for delivery to the airway of a patient at selected higher and lower pressure magnitudes at least as great as ambient atmospheric pressure;   permitting said flow of breathing gas to pass from such a patient;   monitoring said flow of breathing gas to detect an instantaneous flow rate of said breathing gas;   processing selected parameters including said instantaneous flow rate to provide a reference indicia; and   utilizing at least one of said instantaneous flow rate and said reference indicia to select one of said higher and said lower pressure magnitudes for said supply flow of breathing gas.   
     
     
       54. The method as set forth in claim 53 wherein said monitoring of said flow of breathing gas includes continual monitoring thereof. 
     
     
       55. The method as set forth in claim 53 wherein said processing selected parameters includes continual processing thereof. 
     
     
       56. The method as set forth in claim 53 wherein said utilizing at least one of said instantaneous flow rate and said reference indicia includes utilizing both of said instantaneous flow rate and said reference indicia. 
     
     
       57. A method of treating obstructive sleep apnea comprising the steps of: preventing episodes of airway obstruction by applying positive pressure greater than ambient atmospheric pressure within the airway of a patient;   applying said positive pressure by supplying gas at a positive pressure to the airway of such a patient throughout a sequence of alternating inspiratory and expiratory phases of the patient's respiration; and   adjusting said positive pressure in the patient's airway to coordinate the patient's airway pressure with the occurrence of said alternating inspiratory and expiratory phase in a manner that the magnitude of said positive pressure applied during at least some of said inspiratory phases is greater than the magnitude of said positive pressure applied during the expiratory phases immediately following said at least some of said inspiratory phases, respectively; and   maintaining the magnitude of said positive pressure within the patient's airway at a value sufficient to prevent said episodes of airway obstruction during said sequence of alternative inspiratory and expiratory phases.   
     
     
       58. The method as set forth in claim 57 wherein said applying said positive pressure includes substantially continuously applying. 
     
     
       59. The method as set forth in claim 57 wherein said positive pressure applied during at least said inspiratory phases or said expiratory phases is a substantially constant positive pressure. 
     
     
       60. The method as set forth in claim 57 wherein said sequence consists of a single inspiratory phase followed by a single expiratory phase of the patient's respiration. 
     
     
       61. A method of treating obstructive sleep apnea comprising the steps of: preventing episodes of airway obstruction by applying positive pressure greater than ambient atmospheric pressure within the airway of a patient;   applying said positive pressure by supplying gas at said positive pressure to the airway of such a patient throughout a sequence of alternating inspiratory and expiratory phases of the patient's respiration;   adjusting said positive pressure in the airway of a patient such that the magnitude of said positive pressure applied during at least some of said inspiratory phases is greater than the magnitude of said positive pressure applied during the expiratory phases immediately following said at least some of said inspiratory phases, respectively; and maintaining the magnitude of said positive pressure within the patient's airway at a value sufficient to prevent said episodes of airway obstruction during said sequence of inspiratory and expiratory phases.   
     
     
       62. The method as set forth in claim 61 wherein said sequence consists of a single inspiratory phase followed by a single expiratory phase of the patient's respiration. 
     
     
       63. A method of treating obstructive sleep apnea comprising the steps of: preventing episodes of airway obstruction by applying positive pressure greater than ambient atmospheric pressure within the airway of a patient;   applying said positive pressure by supplying gas at said positive pressure to the airway of such a patient;   adjusting said positive pressure in the patient's airway throughout a sequence of patient respiration phases comprised of at least one inspiratory phase and at least one expiratory phase in a manner that the magnitude of said positive pressure in the patient's airway during said inspiratory phases is greater than the magnitude of said positive pressure in the patient's airway during said expiratory phases immediately following the respective said inspiratory phases; and maintaining the magnitude of said positive pressure within the patient's airway at a value sufficient to prevent said episodes of airway obstruction during said sequence of inspiratory and expiratory phases.   
     
     
       64. A method of treating incidents of airway obstruction which occur during sleep comprising the steps of: preventing episodes of airway obstruction by applying positive pressure greater than ambient atmospheric pressure within the airway of a patient;   applying said positive pressure by supplying gas at a positive pressure to the airway of such a patient;   adjusting the pressure of said gas in the patient's airway to coordinate the patient's airway pressure with the occurrence of alternating inspiratory and expiratory phases of the patient's respiration in a manner to maintain said positive pressure in the patient's airway during a sequence of said inspiratory and expiratory phases with the magnitude of said positive pressure during each said expiratory phase being less than the magnitude of said positive pressure during the immediately preceding inspiratory phase, respectively; and   maintaining the magnitude of said positive pressure within the patient's airway at a value sufficient to prevent said episodes of airway obstruction during said sequence of inspiratory and expiratory phases.